In general, a tire mold is provided with an exhaust duct for discharging, to the outside of the mold, air or the like remaining between a green tire and the mold surface. Conventionally, such exhaust duct of a tire mold is formed by means of a vent piece fit into a vent hole (through hole) formed in the mold.
Here, in the case of manufacturing a tire with the use of a tire mold having an exhaust duct formed by means of a vent hole and a vent piece, the rubber is caused to squeeze out into the exhaust duct when the tire is subjected to vulcanization molding, with the result that a number of spews (cylindrical bars) are formed on the outer surface of the vulcanization-molded tire.
In recent years, however, in terms of improving fuel efficiency of vehicles, tires to be mounted on vehicles have been required to be reduced in weight. Along therewith, it has been proposed, as a method of reducing the tire weight, to downsize the bead filler to be disposed on the tire radial direction outside of the bead core embedded in the bead portion (see, for example, Patent Literature 1 (PTL 1)).